Apparatus and method for a retrievable semi-permanent monitoring system

ABSTRACT

An apparatus for retrievable semi-permanent monitoring system includes a casing for a well; a transmission system installed on the outside of the casing or in a wall of the casing; and a sensor array. The sensor array is adapted to couple with the transmission system, and where a wall of the casing is disposed between the sensor array and the transmission system.

BACKGROUND

1. Technical Field

Embodiments of the subject matter disclosed herein generally relate to an apparatus and method for a retrievable semi-permanent monitoring system.

2. Discussion of the Background

Fracture monitoring and reservoir production monitoring may require installing permanent sensor systems, including seismic sensors, in a production well when the distance between wells is too high to monitor the production well from adjacent wells. Pressure, flow and other physical parameters of the production well may also need to be monitored. A permanent sensor system may be installed outside the casing in the well, or cable deployed arrays or memory gauges may be used within the casing.

FIG. 1 depicts an exemplary permanent sensor system installed outside of the casing. Tools 104, which may include seismic sensors such as, for example, geophones, hydrophones, and electromagnetic sensors, in an appropriate housing, may be installed permanently outside casing 102, along with cables 105. Casing 102 may include a production tube 110 through which extracted resources, such as oil, flow from the deposits in the well to a wellhead on the surface, and may be made of any suitable material, such as steel, in any suitable shape. The cables 105 may connect the tools 104 to a telemetry unit 107 and to a computer 108 on the surface. The cables 105 may carry power to the sensors 104 and data transmissions between the tools 104 and the telemetry unit 107. The telemetry unit 107 may be an electronic device for gathering data sent by the tools 104 to send to the computer 108. The computer 108 may be any suitable computing device for processing data from the tools 104.

Tools 104 may be attached to casing 102 using clamps 106 before casing 102 is installed into the well. Sensors 104 may extend to the bottom of casing 102. The space between the outside of casing 102 and a borehole wall 101 may be filled with concrete 103. The tools 104 and cables 105 may be fixed in the well by the concrete 103. Both sensors 104 and cables 105 may be made of any suitable materials to allow them to continue functioning after being encased in concrete 103.

The deployment of a permanent sensor system, such as the sensors 104 and cables 105 depicted in FIG. 1, may be limited by the fact that the permanent sensor system may need to be designed specifically for each well and monitoring application. Wells may be straight or curved, and may need to be monitored for different purposes, requiring different sensors placed at different levels of the permanent sensor system. The sensors needed and their arrangement may need to be decided far in advance in the well drilling program. Additionally, the increased number of levels in the permanent sensor monitoring system may reduce the reliability of the sensors, which may not be repairable or replaceable due to being both encased in concrete and below the surface. Once a permanent sensor system is designed and deployed, it may be extremely difficult to remove or replace. Also, if one sensor fails during operation, that sensor and others connected to it are unusable as these sensors cannot be replaced due to their permanent distribution.

FIG. 2 depicts an exemplary cable deployed array deployed within the casing. Tools 202 may be connected together, and lowered into casing 204, using a cable 203. Concrete 206 may fill the space between casing 204 and a borehole wall 205. A telemetry unit 207 may be the part of the cable deployed array closest to the surface. The cable 203 may connect the telemetry unit 207 to a computer 201 on the surface, and may carry power and data. The cable 203 may be a hepta cable, with seven wires. The tools 202 may be connected to the telemetry unit 207 and to each other by the cables 208, which may be two wire cables. The tools 202 may include equipment for anchoring themselves to the walls of the casing 204 or the borehole wall 205 within the well.

Because cable deployed arrays, for example, as depicted in FIG. 2, are deployed within the casing and/or production tubing, they may not be used when high flow rate fracturation fluid is injected with propants that may grind and destroy the cable, for example, cable 203. A long length of cable may run down the casing, for example, casing 204, from the surface to the telemetry unit.

Thus, there is a need for an apparatus and method that overcomes the above noted problems and allows quick intervention for replacing a failed sensor.

SUMMARY

In various embodiments, an apparatus and method for a retrievable semi-permanent monitoring system are presented. More specifically, in one embodiment, there is an apparatus for retrievable semi-permanent monitoring system that includes a casing for a well; a transmission system installed on the outside of the casing or in a wall of the casing; and a sensor array. The sensor array is adapted to couple with the transmission system, and where a wall of the casing is disposed between the sensor array and the transmission system.

According to another embodiment, there is an apparatus for a transmission system for a retrievable semi-permanent monitoring system that includes a transmission cable and a telemetry unit adapted to transmit and receive data using the transmission cable, and having a transmission coupling system adapted to transmit and receive the data through a wall of a casing.

According to still another embodiment, there is an apparatus for a sensor array for a retrievable semi-permanent monitoring system that includes at least one tool adapted to monitor at least one characteristic of a well or earth surrounding a well and a transmission coupling device adapted to transmit data to and receive data from the at least one tool. The transmission coupling device includes a transmission coupling system adapted to transmit and receive the data through a wall of a casing.

According to yet another embodiment, there is a method for a retrievable semi-permanent monitoring system that includes a step of deploying a sensor array into a casing, a step of coupling the sensor array to a transmission system disposed outside the casing, a step of monitoring with the sensor array a characteristic of the environment and a step of transmitting a measurement of the characteristic from the sensor array inside the casing to the transmission system outside the casing.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments and, together with the description, explain these embodiments. In the drawings:

FIG. 1 depicts an exemplary permanent sensor system installed outside of the casing;

FIG. 2 depicts an exemplary cable deployed array deployed within the casing;

FIG. 3 depicts an exemplary transmission system for a retrievable semi-permanent monitoring system;

FIG. 4 depicts an exemplary retrievable semi-permanent monitoring system with a deployment tool;

FIG. 5 depicts an exemplary retrievable semi-permanent monitoring system after sensor array deployment;

FIG. 6 depicts an exemplary retrievable semi-permanent monitoring system after sensor array deployment with anchored tools;

FIG. 7 depicts an exemplary retrievable semi-permanent monitoring system after sensor deployment with a tool deployed outside the casing;

FIG. 8 depicts an exemplary transmission system for a retrievable semi-permanent monitoring system without clamps;

FIG. 9 depicts an exemplary transmission system for a retrievable semi-permanent monitoring system installed as part of the casing;

FIG. 10 depicts an exemplary cross-section of casing with a modified section between a telemetry unit and a transmission coupling device; and

FIG. 11 depicts an exemplary procedure for deployment of a retrievable permanent monitoring system.

DETAILED DESCRIPTION

The following description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. In various embodiments as illustrated in FIGS. 1-11, an apparatus and method for a retrievable semi-permanent monitoring system is provided.

Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

FIG. 3 depicts an exemplary transmission system for a retrievable semi-permanent monitoring system. A telemetry unit 302 may be attached to the outside of casing 304 with a clamp 307. The clamp 307 may be any suitable device for attaching the telemetry unit 302 to casing 304. The telemetry unit 302 may be attached at any suitable location along casing 304. A transmission cable 303 may be any suitable cable, such as, for example, a hepta cable, for carrying power and data between the telemetry unit 302 and devices, such as computer 301, on the surface. The transmission cable 303 may also be clamped to the outside of casing 304 with the clamps 307. In one application, the transmission cable 303 may be housed in the wall of the casing 304 to be protected from the harsh environment. The telemetry unit 302 and the transmission cable 303 may form a transmission system.

When casing 304 with the attached telemetry unit 302 is installed in the well inside of the borehole wall 305, the transmission system may run from a location in the well, for example, where a first sensor would be placed, to the surface. Concrete 306 may be used to fill in the space between the casing 304 and the borehole wall 305, fixing the telemetry unit 302 in place. The transmission system may thus be permanently installed on the outside of casing 304. Both the telemetry unit 302 and the transmission cable 303 may be made of any suitable materials to allow them to continue functioning if encased in the concrete 306.

The transmission cable 303 may connect the telemetry unit 302 to the computer 301 on the surface through, for example, a surface well head outlet similar to the surface well head outlets used for permanent sensor systems. Power from the surface may be delivered to the telemetry unit 302 through the transmission cable 303. The telemetry unit 302 may include a transmission coupling system 309 which may be, for example, magnetic, acoustic, electro-magnetic, RF based or any other suitable coupling system. The telemetry unit 302 may transmit data received through the transmission coupling system 309 to the computer 301 on the surface through the transmission cable 303. The part of the wall of casing 304 that is located next to the telemetry unit 302 may be modified to facilitate the transmission of data as later discussed with regard to FIG. 10.

FIG. 4 depicts an exemplary retrievable semi-permanent monitoring system with a deployment tool. A tool 408 may include any suitable sensor type for use in a down-hole environment, such as, for example, a hydrophone, geophone, accelerometer, electromagnetic sensor, temperature sensor, pressure sensor, resistivity sensor, flow meter, gravity meter, or oil-water contact device, contained within any suitable housing. A cable 409 may connect multiple tools 408 together. The cable 409 may also connect the tools 408 to a transmission coupling device 407, which may be at the top of the sensor array. The transmission coupling device 407 may be any suitable device for coupling with telemetry unit 402, which may be in concrete 406 outside of casing 404. The transmission coupling device 407 may have a transmission coupling system 414 of the same type as the transmission coupling system 413 used by the telemetry unit 402. For example, if the telemetry unit 402 uses a magnetic transmission coupling system 413, the transmission coupling device 407 may also use a magnetic transmission coupling system 414. The transmission coupling device 407 may receive data, for example, sensor readings and status data, from one or more tools 408, and may be able to perform data communications with the telemetry device 402 across the transmission coupling systems 413 and 414 through the wall of the casing 404. The transmission coupling device 407 may be a stand-alone device, or one, or many, of the tools 408 in the sensor array may include the transmission coupling device 407.

The tools 408, the cable 409, and the transmission coupling device 407 may form a sensor array, such as, for example, a seismic array or other measurement system. The tools 408 in the sensor array may be of the same sensor type, or may be any suitable mixture of sensor types based on the intended application of the sensor array. For example, wells may contain a mixture of oil, water, and gas, and it may be useful to determine if and where the oil-water interface is within the well. Thus, sensor array may have a tool 408 with an oil-water contact device or a gravity meter to detect an oil-water interface.

Cable 409 may carry power, data, or both between the tools 408, or may only be used to connect and support the tools 408 and may not be used for either data or power transmission. For example, the tools 408 may be self-powered, and may communicate with each other and the transmission coupling device 407 wirelessly. The transmission coupling device 407 may be located at any suitable location along the cable 409 in the sensor array to allow for coupling with the telemetry unit 402 and proper positioning of the tools 408. For example, if the telemetry unit 402 is at the bottom of the casing 404, and no tools 408 are to be deployed below the bottom of the casing 404, the transmission coupling device 407 may be at the end of the cable 409, below the tools 408.

Alternatively, the tools 408 and the telemetry unit 407 may be connected to form a sensor array without the cable 409. For example, the tools 408 may be attached to each other and the telemetry unit 407 directly using any suitable connection hardware.

A cable reel 412, a wireline 411, and an attachment device 410 may form a deployment tool used to deploy the sensor array, with the tools 408, into the well through casing 404. The attachment device 410 may be any suitable device for attaching the sensor array to the wireline 411, manipulating the sensor array, and releasing the sensor array, such as, for example, a claw, a hook, a clamp, a magnetic gripper, or a latch system. The sensor array may be attached to the attachment device 410 at the end of the wireline 411. For example, the attachment device 410 may attach to the transmission coupling device 407 of the sensor array, or to specialized attachment hardware on the transmission coupling device 407, or attached above the transmission coupling device 407 on the cable 409, or in any other suitable location in the sensor array. The cable reel 412 may let out the wireline 411, resulting in the attachment device 410 lowering into casing 404 with the sensor array.

The sensor array may be deployed to any suitable depth within the well so that the telemetry unit 402 and the transmission coupling device 407 are aligned, allowing them to couple, and the tools 408 are in a suitable position to gather data for their intended application. In one application, a shoulder (not shown) is attached to an interior of the casing and attachment device 410 is designed to not be able to pass past the shoulder. In this way, alignment between telemetry unit 402 and transmission coupling device 407 is achieved. Alternatively, the depth at which the telemetry unit 402 is located may be known, and the deployment tool may lower the sensor array into the well until the transmission coupling device 407 has reached this known depth. When the sensor array has arrived at the desired location within the well, the attachment tool 410 may release the sensor array and the cable reel 412 may reel the wireline 411 and attachment tool 410 back to the surface. No cable, such as the cable 203 as depicted in FIG. 2, may remain in casing 404, allowing fracture fluid injection to be injected safely. The transmission coupling device 407 may couple with the telemetry unit 402 by, for example, deploying an anchoring device to fix the position of the transmission coupling device 407 against the wall of casing 404 on the other side of the wall from the telemetry unit 402. The telemetry unit 402 and the transmission coupling device 407 may then begin data communications through the transmission coupling systems 413 and 414.

The deployment tool may also be used to retrieve the sensor array. The cable reel 412 may let out the wireline 411 to lower the attachment device 410 to the sensor array within the well. The attachment device 410 may attach to the sensor array, and the cable reel 412 may reel the wireline 411 back in, bringing the attachment device 410 and the sensor array back to the surface. Any anchoring used to hold the sensor array in place may be released after the attachment device 410 attaches to the sensor array and before the cable 412 reels the wireline back in, to allow the sensor array to be moved.

Because the sensor array may be deployable and retrievable separately from the transmission system, sensor arrays with too long of a delivery time for a project may be deployed after the completion of the well and installation of casing 404. Long, complex and expensive sensor arrays may be deployed into the well only when their use is required, which may reduce capital immobilization, as the deployment tool may be used to retrieve such sensor arrays when they are no longer needed in a particular well so that the sensor arrays may be used elsewhere.

The deployment tool may also be used to retrieve the sensor array to perform repairs, replacements, and upgrades on the tools 408 in the sensor array. For example, if one of the tools 408 in the sensor array malfunctions, the deployment tool may be used to retrieve the sensor array to allow for the repair or replacement of the malfunctioning tool 408, and the re-deployment of the sensor array with a repaired or replaced tool 408.

The sensor array may be retrieved from the well so that new tools 408 may be added to the sensor array in addition to or in place of the tools 408 already in the sensor array, before re-deployment of the sensor array. The sensor array may also be retrieved to allow a different sensor array with, for example, different or improved tools 408 from the tools 408 on the retrieved sensor array, to be deployed. Any tool 408 of any sensor type may be used with the transmission system including telemetry unit 402 and a transmission cable 403 installed outside casing 404. The new sensor array may include tools 408 of different sensor types from the retrieved sensor array, but may still use the same transmission system. Deployment and retrieval of sensor arrays may occur during well live time.

FIG. 5 depicts an exemplary retrievable semi-permanent monitoring system after sensor array deployment. The deployment tool may align transmission coupling device 507 of the sensor array with telemetry unit 502 of the transmission system, which may be encased in concrete 506 outside of casing 504. The alignment may be obtained by using a dedicated key, for example, installed inside the casing, or through magnetic force. The transmission coupling device 507 and the telemetry unit 502 may be coupled using compatible transmission coupling systems 511 and 512, which may be used for data transmission and may also be used for power transmission. The telemetry unit 502 and the transmission coupling device 507 may couple even though they are not in physical contact, as they may be separated by the wall of casing 504.

Tools 508 may begin monitoring conditions both within and outside casing 504 and gathering sensor data. For example, a tool 508 with pressure sensor may detect pressure, while a tool 508 with a geophone may gather particle motion data. Data from the tools 508, for example, the sensor data or status data, may be transmitted to the transmission coupling device 507, for example, using the cable 509.

The transmission coupling device 507 may transmit the data from the tools 508 to the telemetry unit 502 using the transmission coupling systems 511 and 512. The telemetry unit 502 may send data received from the transmission coupling device 507 to the surface through transmission cable 503, which may be connected to any suitable device, such as the computer 501. The computer 501 on the surface may thus receive the data from the sensor array through the transmission system.

The transmission system may also allow the computer 501 to send data to the sensor array. For example, the computer 501 may send commands to the tools 508 in the sensor array to start or stop monitoring, change monitoring parameters, perform self-diagnostics, or perform any other suitable action. The data from the computer 501 may be sent to the telemetry unit 502 using the transmission cable 503 and then to the transmission coupling device 507 through the transmission coupling systems. The transmission coupling device 507 may relay the data from the computer 501 to the tools 508.

Power may also be transmitted to the sensor array though the transmission system. For example, power may be transmitted from a power source on the surface through the transmission cable 503 to the telemetry unit 502. The transmission coupling systems 511 and 512 may allow the telemetry unit 502 to transmit power to the transmission coupling device 507 using, for example, electro-magnetic induction or RF induction. The telemetry unit 502 may then distribute power to the tools 508, for example, using the cable 509. The sensor array may also be powered by, for example, any number of batteries in any of the tools 508 and the transmission coupling device 507, or by any suitable manner of generating electricity in a down-hole environment. Each of the tools 508 and the transmission coupling device 507 may have their own power source, or power may be distributed among them, for example, using the cable 509.

FIG. 6 depicts an exemplary retrievable semi-permanent monitoring system after sensor array deployment with anchored tools. After being deployed into casing 604 by the deployment tool, as depicted in FIGS. 4 and 5, the sensor array may be held in position in any suitable manner. For example, as depicted in FIG. 6, tools 608 and transmission coupling device 607 may each be equipped with an anchoring device 610. The anchoring device 610 may be a device attached to the housing of the tools 608 and transmission coupling device 607 of any suitable shape and material to anchor the tools 608 and transmission coupling device 607 within casing 604 or within the well. For example, the anchoring device 610 may be an anchoring arm, which may be a metal wing or scoop that may extend from the housing of a tool 608 and push against the wall of the casing 604, the borehole wall 605, or the concrete 606 until the tool 608 is wedged, or anchored, in the casing 604 or well. The anchoring device 610 may be controllable, for example, through commands sent from the computer 601, allowing the sensor array to be anchored and unanchored as needed within casing 604.

The sensor array may also be held in position within casing 604 using, for example, magnets in the sensor array. Magnets may be placed in, or attached to, the tools 608, or attached elsewhere on the sensor array, and may be used to attach the sensor array to casing 604 magnetically. The magnets may be, for example, electro-magnets, which may be controllable from the computer 601.

FIG. 7 depicts an exemplary retrievable semi-permanent monitoring system after sensor array deployment with one or more tools deployed outside of the casing 704, i.e., the tools extend past the maximum length of the casing 704. In some situations, a sensor array may need to monitor within the well, but outside casing 704, as the casing 704 may not go to the bottom of the well. The sensor array may be constructed with tools 708 that will be below transmission coupling device 707 when the sensor array is deployed.

The transmission coupling device 707 may be aligned with telemetry unit 702 near the bottom (or any other position) of casing 704 during deployment. A tool 708 may be attached below the transmission coupling device 707 by cable 710, so that the tool 708 may be within the borehole wall 705 but outside casing 704 when the sensor array is deployed, while the transmission coupling device 707 is still within casing 704. Concrete 706 may continue past casing 704, and may or may not be in between the tool 708 and the borehole wall 705. In this way, the tool 708 may monitor the well below the lower end of casing 704 while still using the transmission system to communicate with devices on the surface, such as the computer 701. The tool 708 may also receive power from the surface with the rest of the sensor array.

FIG. 8 depicts an exemplary transmission system for a retrievable semi-permanent monitoring system without clamps. The transmission system, including telemetry unit 802 and transmission cable 803, may be installed outside casing 804 without the use of clamps. For example, the transmission system may be temporarily attached to the outside of casing 804 during installation of casing 804 in the well. Once the casing 804 is installed, the transmission system may be permanently fixed in place by concrete 806, which may fill in space between the outside of casing 804 and borehole wall 805, encasing the transmission system.

FIG. 9 depicts an exemplary transmission system for a retrievable semi-permanent monitoring system installed as part of casing. The transmission system, including telemetry unit 902 and transmission cable 903, may be installed as part of casing 904. Casing 904 may be manufactured or modified to enclose the telemetry unit 902 and transmission cable 903, either within the wall of casing 904, or within a secondary housing attached to the wall of casing 904 and designed to accommodate the transmission system. The transmission system may thus be a part of casing 904.

FIG. 10 depicts an exemplary cross-section of a casing with a modified section between a telemetry unit and a transmission coupling device. The part of the wall of casing 1003 that sits between telemetry unit 1001 and transmission coupling device 1002 may be modified to facilitate the use of the transmission coupling systems 1005 and 1006 used to couple the telemetry unit 1001 and the transmission coupling device 1002. A modified section 1004 may be made of any suitable material based on the type of transmission coupling systems 1005 and 1006 being used. The material used in the modified section 1004 may be chosen to enhance the communication and transmission ability of the telemetry unit 1001 and the transmission coupling device 1002.

For example, if the transmission coupling systems 1005 and 1006 are magnetic, a material with a high magnetic permeability, such as ferrite, may be used. The modified section 1004 in the wall of casing 1003 between the telemetry unit 1001 and the transmission coupling device 1002 may include ferrite, as depicted in FIG. 10. The ferrite modified section 1004 may be of any suitable size and shape within the wall of casing 1003, and may include ferrite mixed in any suitable ratio with other materials, such as, for example, the material used to construct the rest of casing 1003.

The ferrite modified section 1004 may have a higher magnetic permeability than the rest of casing 1003, which may facilitate the functioning of magnetic transmission coupling systems 1005 and 1006. This may allow for more effective functioning of the telemetry unit 1001 and the transmission coupling device 1002. For example, higher data transmission rates may be achieved when the telemetry unit 1001 and the transmission coupling device 1002 are separated by the ferrite modified section 1004 instead of the material of the rest of casing 1003, which may be, for example, steel.

If the transmission coupling systems 1005 and 1006 are acoustic, a different material may be used in the modified section 1004. For example, a material with lower acoustic impedance than the material used in the rest of casing 1003, such as, for example, aluminum, may be used in the modified section 1004. Other materials may be used in the modified section 1004 depending on the type of transmission coupling systems 1005 and 1006 used by the telemetry unit 1001 and the transmission coupling device 1002.

FIG. 11 depicts an exemplary procedure for deployment of a retrievable permanent monitoring system. In block 1101, a transmission system may be attached outside of the casing. For example, as depicted in FIG. 3, a transmission system including the telemetry unit 302 and the transmission cable 303 may be attached to the outside casing 304 with the clamps 307 and 308. Alternatively, the transmission system may be deployed outside casing as depicted in FIGS. 8 and 9, or in any other suitable manner. The casing may be installed within a well after the transmission system is attached.

In block 1102, space between a borehole wall and the casing may be filled in. For example, as depicted in FIG. 3, the concrete 306 may be used to fill in the space between the borehole wall 305 and casing 304, encasing and permanently installing the transmission system. Any other suitable material may also be used to fill the space between the borehole wall and the casing.

In block 1103, a sensor array may be deployed inside the casing. For example, as depicted in FIG. 4, the deployment tool including the cable reel 412, the wireline 411, and the attachment device 410 may be used to the deploy the sensor array including the tools 408, cable 409, and transmission coupling device 407, into the casing 404. The transmission coupling device 407 may be aligned with the telemetry unit 402, and the sensor array may be fixed in place by, for example, anchoring as depicted in FIG. 6. As depicted in FIG. 5, the tools 508 may all be contained within the casing 504, or, as depicted in FIG. 7, some of the tools 708 may be below the end of the casing 704.

In block 1104, the sensor array and transmission system may be used for monitoring the casing, well, and the earth around the well. For example, as depicted in FIG. 5, the tools 508 of the sensor array may gather data on the environment within the casing 504, the well, and the surrounding earth, based on their sensor types. The data gathered by the sensors in the tools 508 may be transmitted through cable 509 to the transmission coupling device 507. The transmission coupling device 507 may transmit the data to the telemetry unit 502, which may send the data to a device on the surface, for example, the computer 501, through the transmission cable 503. The incoming sensor data may be monitored by an operator of the computer 501, or by automated systems. The computer 501 may also be used to send data, such as commands, to the sensor array during monitoring.

In block 1105, if the sensor array needs removal, flow proceeds to block 1106. Otherwise, flow proceeds back to block 1104, where monitoring may continue. The sensor array may be removed from the casing when, for example, a tool or transmission coupling system is malfunctioning and in need of repair or replacement; different, new or upgraded tools, sensors in the tools, or transmission coupling systems are going to be deployed; activities within the well require removal of the sensor array, or the well no longer needs monitoring.

In block 1106, the sensor array may be removed from the casing. If the sensor array needs to be removed, the deployment tool, for example, as depicted in FIG. 4 may be used to retrieve the sensor array from the casing. The cable reel 412 may let out the wireline 411 until the attachment device 410 attaches to the sensor array. The sensor array may be unfixed from its position, for example, by unanchoring, and the cable reel 412 may reel the sensor array back to the surface, retrieving the sensor array from the casing 404.

In block 1107, if further monitoring is needed, flow proceeds back to block 1103, where a sensor array may be deployed within the casing. Otherwise, flow proceeds to block 1108. Further monitoring may be needed after the sensor array has been retrieved, for example, when the sensor array was retrieved for repair or replacement of components or to be replaced with a new sensor array, when removal of the sensor array was temporary to allow for activities within the well, when environmental conditions within or around the well require further monitoring, or in any other situation where monitoring of the well may need to resume. The sensor array deployed after going back to block 1103 may be a different sensor array than the sensor array retrieved in block 1106, or may be the same sensor array, which may or may not have been modified.

In block 1108, the transmission system may be left in place. Because the transmission system may be encased in concrete, the transmission system may be permanent, and may stay in place even after the well no longer appears to need monitoring by the sensor array. The transmission system may be used again should the well end up requiring monitoring in the future.

The disclosed exemplary embodiments provide an apparatus and method for a retrievable semi-permanent monitoring system. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.

Although the features and elements of the present exemplary embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein.

This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims. 

What is claimed is:
 1. An apparatus for retrievable semi-permanent monitoring system comprising: a casing for a well; a transmission system installed on the outside of the casing or in a wall of the casing; and a sensor array, wherein the sensor array is adapted to couple with the transmission system, and where a wall of the casing is disposed between the sensor array and the transmission system.
 2. The apparatus of claim 1, wherein the transmission system comprises a telemetry unit and a transmission cable.
 3. The apparatus of claim 2, wherein the sensor array comprises at least one tool and a transmission coupling device.
 4. The apparatus of claim 1, wherein the transmission system is fixed in place by concrete disposed between the casing and a borehole wall.
 5. The apparatus of claim 3, wherein the at least one tool comprises a sensor, and wherein the sensor is one of a hydrophone, a geophone, an electromagnetic sensor, an accelerometer, a temperature sensor, a pressure sensor, a resistivity sensor, a flow meter, a gravity meter, and an oil-water contact device.
 6. The apparatus of claim 3, wherein: the telemetry unit comprises a first transmission coupling system; and the transmission coupling device comprises a second transmission coupling system, and wherein the first transmission coupling system and the second transmission coupling system are adapted to couple the telemetry unit and the transmission coupling device.
 7. The apparatus of claim 6, wherein the first transmission coupling system and the second transmission coupling system are one of magnetic, acoustic, electro-magnetic induction based, and RF based.
 8. The apparatus of claim 6, further comprising, a computing device, wherein the computing device is connected to the telemetry unit by the transmission cable.
 9. The apparatus of claim 8, wherein the telemetry unit is adapted to receive data from and transmit data to the transmission coupling device through the first and second transmission coupling systems and the computing device through the transmission cable.
 10. The apparatus of claim 8, wherein the telemetry unit is adapted to receive power through the transmission cable and to transmit power to the transmission coupling device through the first and second transmission coupling systems.
 11. The apparatus of claim 3, wherein the casing comprises a modified section disposed between the telemetry unit and the transmission coupling device, and wherein the type of the modified section is based on the type of the first and second transmission coupling systems.
 12. The apparatus of claim 1, further comprising a deployment tool adapted to deploy the sensor array into the casing and retrieve the sensor array from the casing.
 13. The apparatus of claim 3, wherein at least one tool of the tool array is disposed outside of the casing when the sensor array is deployed within the casing.
 14. An apparatus for a transmission system for a retrievable semi-permanent monitoring system comprising: a transmission cable; and a telemetry unit adapted to transmit and receive data using the transmission cable, and comprising a transmission coupling system adapted to transmit and receive the data through a wall of a casing.
 15. The apparatus of claim 14, further comprising at least one clamp adapted to attach the telemetry unit to the casing, and at least one clamp adapted to attach the transmission cable to the casing.
 16. The apparatus of claim 14, wherein the telemetry unit is further adapted to receive power through the transmission cable and the transmission coupling system is further adapted to transmit power.
 17. An apparatus for a sensor array for a retrievable semi-permanent monitoring system comprising: at least one tool adapted to monitor at least one characteristic of a well or earth surrounding a well; and a transmission coupling device adapted to transmit data to and receive data from the at least one tool and comprising a transmission coupling system adapted to transmit and receive the data through a wall of a casing.
 18. The apparatus of claim 17, wherein the transmission coupling system is further adapted to receive power, and the transmission coupling device is further adapted to transmit power to the at least one tool.
 19. A method for a retrievable semi-permanent monitoring system comprising: deploying a sensor array into a casing; coupling the sensor array to a transmission system disposed outside the casing; monitoring with the sensor array a characteristic of the environment; and transmitting a measurement of the characteristic from the sensor array inside the casing to the transmission system outside the casing.
 20. The method of claim 19, further comprising: before deploying the sensor array, attaching the transmission system outside the casing; installing the casing in a well; and filling space between the casing and a borehole wall of the well with concrete. 